The invention relates to surface functionalized diamonds and diamond crystals. The surface functionalized diamonds and diamond crystals exhibit improved bond strengths with coatings and matrix materials. In particular, the invention relates to methods for producing surface functionalized diamonds and diamond crystals that exhibit enhanced bond retention in abrasive products.
Saw blades, grinding wheels, drill bits, and similar abrasive products (hereinafter xe2x80x9cabrasive productsxe2x80x9d), which are used in machining and grinding of hard materials, often comprise diamonds and diamond crystals (hereinafter xe2x80x9cdiamond crystalsxe2x80x9d). The diamond crystals are placed in a matrix and are bonded to a tool or device, such as a grinding wheel and a saw blade segment, to form an abrasive product. The diamond crystals comprise naturally occurring diamonds or manufactured (synthetic) diamonds. The manufactured diamonds comprise any synthetic diamond, such as, but not limited to, diamonds manufactured by a high-pressure, high-temperature (HPHT) processes and chemical vapor deposition (CVD) processes. The bond of the matrix and diamond crystals is referred to as an abrasive bond. The abrasive bond is formed by a mechanical or chemical processes, and may comprise metallic, vitreous, or resin bonds.
Some diamond crystals, which are used in abrasive products, comprise a coating layer of metal for enhancing an adhesive bond strength. The coatings may comprise metal films, such as titanium, nickel, copper, and chromium films. The metal coatings are deposited on diamond crystal surfaces by an appropriate process, such as, but not limited to, evaporation and sputter deposition in vacuum. The metal coatings form bonds with the surfaces of the diamond crystals.
Abrasive products often fail during use. The failure can be caused by separation of the diamond crystal from the matrix or de-bonding of the metal coating from the diamond crystal. Improving a bond strength between the diamond crystal and the matrix metal and between the diamond crystal and the metal coating will lead to improved abrasive products tools, increased abrasive product life and value, and superior abrasive product performance.
The invention sets forth a method for improving a bond strength between a diamond crystal and a matrix material and between the diamond crystal and the metal coating. The method comprises functionalizing a diamond crystal to create diamond crystal surface sites that promote strong bonds with both the metallic coating and the matrix, such as a vitreous or metallic matrix. The functionalizing comprises hydrogenating a diamond crystal; chlorinating the hydrogenated diamond crystal; and exposing the chlorinated diamond crystal to a metal precursor. The exposing step deposits an ultra-thin metal-containing layer on surfaces of the diamond crystals. The diamond crystal formed by the functionalizing method possesses strong bonds with the ultra-thin metal layer at surface sites to prevent separation. The ultra-thin metal layer forms strong bonds with the matrix material. The functionalized diamond crystal can then be used in abrasive products.
These and other aspects, advantages and salient features of the invention will become apparent from the following detailed description, which, when taken in conjunction with the annexed drawing, where like parts are designated by like reference characters throughout, disclose embodiments of the invention.